There are known biosensors which use detection elements such as surface acoustic wave devices to perform measurement regarding properties of liquid analytes or measurement regarding components of the liquid (for example, see PTLs 1 through 3).
For example, a biosensor using a surface acoustic wave device is configured with a detection unit, which reacts with components included in analyte specimens, on a piezoelectric substrate. The properties or components of the liquid analyte are detected by measuring change in surface acoustic waves propagating through this detection unit. Measurement methods using surface acoustic wave devices and the like are advantageous over other measurement methods (the enzyme method, for example), in that multiple detection formats can be handled.
However, none of the conventional biosensors using detection elements such as surface acoustic wave devices have mechanisms to suction liquid themselves. This has necessitated, in order to feed the analyte to the detection unit, a task of first suctioning the specimen using equipment such as a micropipette and then feeding the suctioned specimen to the detection unit, which makes the procedures for measurement cumbersome. Also, the need for separate equipment increases the scale of the overall measurement apparatus.
On the other hand, there are known biosensors using a detection method different from that using detection elements such as surface acoustic wave devices. A reagent including an enzyme or the like is coated on a measurement electrode, the specimen is made to react with that portion, and change in current at the measurement electrode is read (see PTL 4).
PTL 4 discloses a technique in which the biosensor itself can suction specimens by capillary action. A slender specimen supply channel is extended to the portion of the measurement electrode where the reagent is coated and the specimen is suctioned to the portion electrode where the reagent is coated by capillary action.
Note that the method to measure specimens by coating the measurement electrode with a reagent including an enzyme or the like as in PTL 4 is limited in test items which can be measured, and accordingly is inconvenient in cases where testing of multiple items is desired.
Now, the structure of the measurement portion of the biosensor described in PTL 4 is one where a reagent is coated on the electrode, so the thickness of the measurement portion is that of the electrode, which is very thin. Accordingly, the slender specimen supply channel can be led up to the measurement portion without the specimen supply channel being blocked partway though.
On the other hand, detecting devices of biosensors using detection elements such as surface acoustic wave devices are formed using piezoelectric substrates or the like, so the detection element has a certain thickness. Accordingly, if the technique in PTL 4 is applied, the specimen supply channel will be blocked by the detection element, so feeding the specimen solution to the detection unit is difficult.
Accordingly, it has been found desirable to provide a biosensor including a suctioning mechanism, even in a case of using a thick detection element such as a surface acoustic wave device.